Example embodiments relate to wireless communication systems, and more particularly, to wireless communication systems that perform a resource-mapping operation and a channel-estimating operation, and methods of operating the wireless communication systems.
Various types of physical channels and pilot signals in a wireless communication system have their own roles according to their characteristics. For example, in a downlink, there are physical channels such as a physical broadcast channel (PBCH) that provides basic information such as the number of transmission ports of a base station, a system frequency band, and a system frame number; a physical downlink shared channel (PDSCH) that corresponds to a data channel, a physical downlink control channel (PDCCH) that is a control channel used in PDSCH transmission, a physical control format indicator channel (PCFICH) that provides an indication of a transmission format of the PDCCH, a physical hybrid Automatic Repeat reQuest (ARQ) indicator channel (PHICH) that transmits hybrid ARQ information, and an enhanced physical downlink control channel (EPDCCH) that functions as an additional control channel. Pilot signals used in detecting these physical channels may include at least one of cell-specific reference signals (CRSs), demodulation reference signals (DM-RSs), multicast-broadcast single-frequency network (MBFSN) reference signals, and position measurement reference signals. The pilot signals may be referred to as reference signals for channel estimation. A channel, through which a corresponding physical channel passes, is estimated so that a data symbol corresponding to each of the physical channels may be detected and decoded. Such channel estimation is performed by using the pilot signals, and the pilot signals are respectively arranged so that times when the physical channels are transmitted and time-frequency resource areas may be estimated. Also, as the number of pilot signals is increased, an estimating performance of a receiver channel may be further improved. However, as the number of pilot signals is increased, a data transmission rate is relatively reduced such that there is a limitation to increasing the number of the pilot signals.